TABLE 3

Inhibition of various AC isoforms and sGC by TNP-nucleotides mAC, sAC, and sGC activity was determined as described under Materials and Methods in the presence of Mn²⁺. Reaction mixtures contained TNP-nucleotides at concentrations from 1 nM to 100 μM as appropriate to generate saturated inhibition curves. Inhibition curves were analyzed by nonlinear regression and were best-fitted to monophasic sigmoidal curves. K_i values were calculated from IC₅₀ values using the previously determined K_m values (Gille et al., 2004). K_m for sAC was 380 ± 20 μM, and V_max was 760 nmol/mg/min. Data shown are the means ± S.D. of three to six experiments performed in duplicates.